Every cat can go to level 10. Everyone starts at level 1, no matter what their age.

Every cat can level up if they command (/whatever) enough times. Leveling up means that they are more skilled in all of their commands. And that means they can get closer to be nominated for leader and deputy!

If your cat is level 10, they cannot level up again, for they are the best warrior/medicine cat, etc. that they can be! So congratulations on that!